The invention provides a pneumatic support device which saves time and labor and is high in work efficiency. The pneumatic support device comprises a base, an internal leg, a shell, a pneumatic lifting device and a pneumatic limiting device. The pneumatic lifting device is connected between the top of the internal leg and the inside of the top of the shell, a third limiting hole is transversely formed in the bottom of the shell, the rear side of the third limiting hole is horizontally sleeved with a tube cylinder part, and the other end of the tube cylinder part is connected with the pneumaticlimiting device in a butted mode. In the pneumatic support device, an air suspension system is adopted, and an air source is used as power, so that the pneumatic support device conforms to technological development tendency; the pneumatic lifting device and the pneumatic limiting device are used as transmission devices, complex complete transmission mechanisms of gears, lead screws, nuts and thelike are omitted, labor consumption is reduced, the operation is simple, and the device is environmentally friendly and has high economic and social benefits.